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Don't Mess with Mama

Attached Images

This is a Fish Crow V Immature Great Blue Heron.

I photographed this at rookery in Tampa Bay.

From my experience, it's not the size of the bird in the fight, it's the size of the fight in the bird.
Just don't mess with Mama. I have seen tiny birds attack very large birds protecting their nest.
This behavior would be completely out of character if not for protecting a nest.

I have also noticed that birds are more aggressive protecting their babies than they are their eggs.

Great new forum, James! Great behavior captured and I definitely agree with your conclusion. A couple of weeks ago a bald eagle hovered over a pond where a pair of Canada Geese raised 5 goslings. One of the geese flew up like a raptor attacking the eagle. A flock of crows came to support the goose and they started mobbing the eagle who then decided to leave without attacking the goslings. Speak about team work. :)

I am really glad you posted this. In a thread at DPReview (http://forums.dpreview.com/forums/re...ssage=28374673), someone is showing incredible images of an Eastern Kingbird riding on the back of a Bald Eagle. I don't know the poster and I haven't seen such behavior myself. Hence I was assuming it's a piece of art courtesy of Adobe...

We've seen a number of really interesting fights like this around here. We've had mockingbirds attack and eagle and drive it off, riding on it's back and pecking away at it's back. The same thing happened recently when a red-tailed hawk came too close to the purple martin houses and a mob of purple martins went after the hawk. One bird, I'm assuming it was a martin, ended up on the hawks back and was still there as it flew out of our sight.

All of these have happened when birds had chicks in the nest, but I've also seen it in non-nesting season as well.

Hi James- You are right on the money and so is Axel. Great start to the forum because I can bring up life-history strategy! First, though, this is a great image with the crow having two points of contact with the nasty heron (see below).

Some species are long-lived and tend to produce small numbers of offspring every year. Some are short-lived and produce large broods. Across species there is a trade-off between life-span and annual output of young. Having kids takes years off your life!!

So, if there is any risk to a small bird attacking a larger predatory one, species that do not live long will tend to take big risks to save their offspring. Long-lived species tend to "shrug their shoulders" and wait for another year. For them it is very important that they live to reproduce again so they are not risk-takers when it comes to their own lives.

The image of a crow beating up on a heron is quite typical. Herons have a bad rap in the bird world, whether deserved or not, and often elicit mobbing reactions in other birds. Night-Herons are a real threat to many species. For example, they will visit a tern colony at night and gobble up as many chicks as will fit in their stomachs (I've heard of workers finding 20-30 tern chicks in their stomachs). Needless to say, anything that looks like a heron gets mobbed by terns at the colony.

Final thought- maybe it's not so risky for a small bird to chase a large predatory one like an eagle, so long as the smaller one makes a lot of noise and keeps the larger one on the run.

I have also noticed that birds are more aggressive protecting their babies than they are their eggs.

Am I full of it or are these creditable observations?
Thanks James

James you are right. There are lots of scientific papers about "parental investment in birds".

In nature, things works as a trade off between benefits and costs (just like in the human world!) but the currency is the energy invested in a process. A pair of breeding birds have a limited budget of energy to invest in their current breeding attemp and they try to optimize it: invest as less energy as they can to raise as much offsprings as possible. Nest defense is very costly in terms of energy, and risky, because the parents risk their lives to protect their investment (the offspring). It is very simple, you invest more energy, and take more risk, to defend a valuable investment. A 5 days old chick is a more valuable investment than a 2 days old egg and you will protect more actively. If a a fox prey on a nest with two fresh eggs the parents should lose a small part of their seasonal budget for breeding but they will have enough energy to invest in a second breeding attemp. But, if a fox prey on a nest with two, ready to flight, full grown chicks, the parents will have no more energy to invest on a second clutch. That is the reason why birds defend with more intensity their chicks than their eggs.

A typical example of this model can be seen on ground nesting birds like killdeer or nighthawk. If a fox found a nest containing fresh eggs the brooding female would fly and scape to protect her life (the investment in the nest is low and do not deserve the adult bird to put in risk her life) but if the nest contains chicks, the female would defend the nest with very active and very risky strategies (highly cost) like injury feigning displays, distraction displays, direct attack to the predator and so on, because the value of the nest is high enough for her as to put her life under risk.John a very interesting post:)

I see this sort of thing all the time, mostly with Red-winged Blackbirds and Grackles attacking Crows, and both attacking raptors, at this time of year. Here's an image I took last month of an American Crow and a Common Grackle having a go at a Red-tailed Hawk, over my back yard. A more extreme example is when large numbers of Crows mob large Owls, sometimes striking them. As an aside, if you ever doubt that some birds are very capable of driving off unwanted intruders, just try approaching a N.Goshawk anywhere near a nest containing young - very scary!.

Great explanation Juan. Dawkins wrote a paper on this once upon a time, and said that organisms don't commit the "Concorde Falacy". Essentially he said that animals make decisions based on the expectation of future success not how much they have invested already. If decision makers had done this the Supersonic Concorde would likely never have been completed! Just another way of looking at things. An animal is more likely to risk his neck for his chicks than his eggs because the chicks have a greater chance of growing up than the eggs do.

Oh boy I think we've crossed the line here. Let's get back to taking pictures!

I am involved in a Common Tern Recovery Program on a lake in South Central Ontario. In 2005 not one single chick survived to fledging. We assumed that the gulls that were taking over the colony were the culprits but I did see a juvenile night heron roosting in a tree that year.

It never occurred to any of us that a night heron could have been the predator!

I just know I am going to learn lots from this forum! Thanks for sharing!

Hi James- You are right on the money and so is Axel. Great start to the forum because I can bring up life-history strategy! First, though, this is a great image with the crow having two points of contact with the nasty heron (see below).

Some species are long-lived and tend to produce small numbers of offspring every year. Some are short-lived and produce large broods. Across species there is a trade-off between life-span and annual output of young. Having kids takes years off your life!!

So, if there is any risk to a small bird attacking a larger predatory one, species that do not live long will tend to take big risks to save their offspring. Long-lived species tend to "shrug their shoulders" and wait for another year. For them it is very important that they live to reproduce again so they are not risk-takers when it comes to their own lives.

The image of a crow beating up on a heron is quite typical. Herons have a bad rap in the bird world, whether deserved or not, and often elicit mobbing reactions in other birds. Night-Herons are a real threat to many species. For example, they will visit a tern colony at night and gobble up as many chicks as will fit in their stomachs (I've heard of workers finding 20-30 tern chicks in their stomachs). Needless to say, anything that looks like a heron gets mobbed by terns at the colony.

Final thought- maybe it's not so risky for a small bird to chase a large predatory one like an eagle, so long as the smaller one makes a lot of noise and keeps the larger one on the run.

Great informative post John. Thanks - by the way - for directing me to this. :) Interesting as you say that long-lived species 'shrug' their shoulders. For example an Australian Magpie (a species of butcherbird really - Cracticus tibicen) is a common bird, beautiful too, and may live 25-30 years. In that time a female apparently is lucky to raise TWO young that end up successfully reproducing themselves or so I recently read in a book written by a professor, who spent 10 years compiling the info for her great little reference book. So every year out of a brood of four/five most will not survive to successful adulthood. Sad, but that is how it is isn't it? Maggies (as we Aussies affectionately call them) are far from being endangered. :)

It's been some years since I've studied animal behaviour (our school biology didn't have it, but the Biology Olympiad had), and i remember solving many of these "What will the bird do?" or "Why does the bird do it?" problems!

A question, can you recommend any books on this subject? I am sure many here would love to fread up more!

There are but they tend to be fairly technical. IMO one of the most insightful books written on the subject of the evolution of animal behaviour was by Richard Dawkins and was entitled "The Extended Phenotype"- essentially laying out the concept of how genes can affect the behaviour of both of the host body and beyond to other individuals. It was in this book that Dawkins also first introduced the concept of a "meme"- a memory element that is passed on through cultural transmission or not and so essentially goes through a process of natural selection as genes do.

I have photographed many small birds viciously attacking much larger and generally more aggressive predators when protecting their young or their hunting grounds.

The thing that continues to amaze me is I often see "Willy Wagtails" attacking our largest Raptor the "Wedgetail Eagle" which they do by flying behind a bird twenty times their size and nipping their tail feathers until they drive them away from their nesting area.

I have attached a link showing one of these brave little birds attacking an Osprey in Perth Western Australia.